The present disclosure is directed towards a hydraulic assembly for a multiple-circuit vehicle brake system. The hydraulic assembly comprises a pressure generator for generating a hydraulic pressure in the brake circuits independently of the driver.
Conventional vehicle brake systems may be actuated either by a driver or independently of a driver. A braking operation initiated by the driver is referred to also as a service braking operation. In the course of a service braking operation initiated by the driver or independently thereof a driving safety system may cause a braking operation independently of the driver. This is referred to as a system braking operation that may be chronologically superimposed on a service braking operation or occur at a separate time to a service braking operation. Known driving safety systems comprise for example an anti-lock braking system (ABS), electronic stability control (ESC and/or ESP) and similar systems.
In conventional vehicle brake systems, in the case of a service braking operation, the hydraulic pressure in the brake circuits is generated by the driver himself. For this purpose the brake circuits are coupled hydraulically to a master cylinder, which is actuated by the driver in a known manner by means of a brake pedal.
In modern vehicle brake systems the generation of hydraulic pressure during a service braking operation may be effected also by the means of a pressure generator that is actuable independently of the driver. As a rule such a pressure generator is a hydraulic pump, which is for example part of an electrohydraulic vehicle brake system or a regenerative vehicle brake system (“hybrid brake system”).
In an electrohydraulic brake system, according to the “brake-by-wire” principle the master cylinder during the service braking operation is fluidically uncoupled from the brake circuits. The generation of hydraulic pressure is effected here by means of the hydraulic pump, which is triggered in dependence upon an actuating state of the brake pedal. In a regenerative vehicle brake system, during a service braking operation the master cylinder is likewise hydraulically uncoupled from the brake circuits. Decelerating of the vehicle is effected in this case by means of a generator that charges a vehicle battery. If the driver requires a greater vehicle deceleration than the generator can deliver, the hydraulic pump generates a supplementary hydraulic pressure in the brake circuits. This process is referred to also as “blending”.
From DE 10 2007 047 208 A1 and corresponding U.S. Patent Application Publication No. 2010/0219678 A1, both of which are incorporated by reference herein in entirety, a dual-circuit electrohydraulic brake system is known. The brake system comprises two electric motor-driven pressure generators, which are realized in the form of a dual-circuit fluid feed pump. By means of the dual-circuit fluid feed pump an individual hydraulic pressure may be generated in each of the two brake circuits.